1. Field of the Invention
The invention relates to the field of security locks for doors.
The invention particularly relates to the field of lock strike plate assemblies of special construction whereby installation of the strike plate to the door frame reinforces the door frame.
The invention specifically relates to the field of reinforced strike plate assemblies to which security chain latch means may be coupled for more secure operation of a security chain used in conjunction with the strike plate assembly.
2. Prior Art
A strike plate, generally manufactured of brass or steel, is mounted to a door frame and is provided with an opening through which the latch or deadbolt of a lock mounted on a door may project and be captively retained therein to secure the door in a locked position. The strike plate is generally maintained in position by two screw fasteners. An impulse of force applied to the door is often sufficient to tear the strike plate from its moorings on the door frame so as to permit the person applying such force free access to the room intended to be secured by the locked door. A maximum security strike, "strike-1." (.TM.), manufactured by M.A.G. Eng. and Mfg., Inc. is made of high quality 12 gauge steel and is said to add tremendous strength to a doorjamb. It is retained by four two inch and two one inch long hardened screws and is said to be many times stronger than regular strike plates. Nevertheless, the strike plate is mounted only to one side of the door frame, within the doorjamb, and relies on the additional screw fasteners for strength but contributes little to actually reinforcing the door frame itself.
In U.S. Pat. No. 4,027,907 issued to the inventor herein on June 7, 1977, a generally L-shaped strike plate is disclosed in which screw fasteners are employed on the interior surface of the door frame and on the jamb surface of the door frame to retain the L-shaped strike plate in position. The addition of screw fasteners on two orthogonal surfaces of the door frame for mounting the generally L-shaped strike assembly significantly improves the strength of the device when it is positioned on a door and used in cooperation with a door locking device.
The same patent further discloses a security chain latch housing which is pivotally coupled to the exterior surface of the generally L-shaped strike assembly. Because of the orthogonal arrangement of the screw fasteners in mounting the striker to the door frame, the associated chain latch assembly is also strengthened when compared with conventional means for affixing a chain latch to a door frame. The usual manner in which such chain latch assemblies are coupled to the door frame is by means of two threaded screw fasteners. With a door ajar and security depending upon the strength of the security chain assembly, prior art devices are prone to fail since an impact readily removes the two screw fasteners holding the prior art chain latch assembly to the door frame.
It is an objective of the present invention to overcome the disadvantages of the prior art with respect to the strength of strike plate assemblies and the mounting of security chain latch means.
It is a particular objective of the invention to provide a strike plate assembly which mounts to a door frame in such a manner as to actually reinforce the door frame and make the frame a more integral part of the securing of the door than has been hitherto available.
It is another objective of the invention to provide a reinforced strike plate assembly to which security chain latch means may be coupled in a manner so as to take advantage of the reinforced means whereby the strike plate assembly is mounted to the door frame.